The present invention relates to a chemical mechanical polisher or chemical mechanical polishing (CMP) machine, and more particularly to a diaphragm between a rotary unit and a holder of a pad conditioner in the CMP machine.
Two planarization techniques, specifically spin-on-glass (SOG) and chemical mechanical polishing (CMP), have been widely used in industry. As the semiconductor fabrication technique has approached the deep sub-micron regime, the required level of planarity can not be achieved using the technique of spin-on-glass. The only technique to provide the required level of planarity in a very large scale integration (VLSI) or ultra large scale integration (ULSI) is chemical mechanical polishing. In the chemical mechanical polishing process, a polishing procedure similar to that used by a grinder is used with the aid of a chemical reagent. The uneven surface profile is thus smoothed. With an appropriate control of the polishing parameters, about 90% of planarity can be achieved using chemical mechanical polishing.
A chemical mechanical polisher or chemical mechanical polishing (CMP) machine operates by holding and rotating a wafer with a holder on a polishing pad supplied with polishing slurry thereon. After an extended polishing time, some abrasive particles in the polishing slurry become embedded and trapped in the polishing pad, causing the performance of the polishing pad to decay with time. For example, the substrate polished on the polishing pad can be scratched and damaged from the embedded abrasive and thus decreasing the polishing uniformity. Therefore, a pad conditioner is generally employed in a CMP machine to recondition the used polishing pad and recover original polishing condition and state. Typically, the pad conditioner has a rotary unit and a holder. In the bottom of the holder is a diamond-coated conditioning disk used to remove embedded abrasive and contaminated slurry and to recover original polishing condition. Further description about the pad conditioner of a CMP machine may be found in U.S. Pat. No. 6,200,199, the entirety of which is incorporated by reference.
A conventional pad conditioner generally includes a robot arm. A rotary unit is assembled in one end of the arm and activated with a power supply device to force the holder thereunder to rotate. The diamond disk on the bottom of the holder is employed to remove embedded abrasives and contaminated slurry on a polishing pad and to recover the original polishing condition of the polishing pad. In addition, an elastic and flexible rubber diaphragm is disposed between the rotary unit and the holder. During the conditioning operation, the rubber diaphragm can become jammed and contorted, forming a crease because of relative dislocation of the rotary unit and the holder. The rubbing of the diaphragm against the sidewall of the rotary unit and the holder generates friction and force on the diaphragm. The accumulated strain on the diaphragm caused by the friction results in fatigue and wear, and consequently results in breakage. Therefore, lifetime of the diaphragm is reduced. Maintenance frequency of the CMP machine is raised, resulting in a decrease of the throughput of the CMP machine.
In one aspect, the invention is directed to a diaphragm for chemical mechanical polisher that has an elastic layer to connect a rotary unit and a holder and a fibrous layer attached on the elastic layer to reinforce strength of the elastic layer. The holder is fitted into the rotary unit, and a gap between the rotary unit and the holder is sealed by the elastic layer.
Implementations of the invention may include one or more of the following features. The fibrous layer may include a net structure, the elastic layer may be composed of rubber, the elastic layer and the fibrous layer may be annular, and the diaphragm may rotate with the rotary unit.
In another aspect, the invention is directed to a diaphragm for a chemical mechanical polisher. The diaphragm has an external sealing ring mounted on an internal sidewall of a rotary unit, an internal sealing ring mounted on an external sidewall of an holder, and a connect ring smoothly connected between the external sealing ring and the internal sealing ring. The holder is fitted into the rotary unit, and the external sidewall of the holder is adjacent to the internal sidewall of the rotary unit. The width of the connect ring is designed according to a gap distance and a maximum relative shift distance between the external sealing ring and the internal seal ring.
Implementations of the invention may include one or more of the following features. The external sealing ring, the connect ring and the internal ring may be integrally formed. Each of the external sealing ring, the connect ring, and the internal ring may be composed of a fibrous layer and an elastic layer. The fibrous layer may include a net structure, and the elastic layer may be composed of rubber. The diaphragm may rotate with the rotary unit.
In another aspect, the invention is directed to a chemical mechanical polisher. The polisher has a rotary unit, a holder fitted into the rotary unit and a diaphragm composed of a rubber layer and a fibrous layer connects the rotary unit and the holder, and seals a gap between the rotary unit and the holder.
Implementations of the invention may include one or more of the following features. A carrier may hold a substrate, and a polishing surface may polish the substrate. The rotary unit, holder and diaphragm may be part of a conditioner to condition the polishing surface. A bottom surface of the holder may recondition a polishing pad by rotating thereon. The bottom of the holder may comprise a diamond layer. The fibrous layer may include a net structure, the elastic layer may be composed of rubber, the diaphragm may be annular, and the diaphragm may rotate with the rotary unit.
A potential advantage of the invention is that the strength and durability of the diaphragm can be increased to prevent failure during operation and improve the lifetime of the diaphragm.